Prostacyclin derivatives are useful pharmaceutical compounds possessing pharmacological activities such as platelet aggregation inhibition, gastric secretion reduction, lesion inhibition, vasodilation and bronchodilation. Treprostinil is a prostacyclin analogue, having the following chemical structure:

Treprostinil sodium solution is marketed as Remodulin® and Tyvaso® for treatment of pulmonary arterial hypertension.
Process for preparation of treprostinil, treprostinil derivatives and intermediates useful in preparation of treprostinil are described in U.S. Pat. Nos. 4,306,075; 6,700,025; 6,809,223 and 6,765,117. U.S. Pat. No. 4,306,075 (col. 40, I. 41-62) discloses a general procedure for preparation of pharmacologically acceptable salts of treprostinil, where preparation of an inorganic salt of treprostinil can be carried out by dissolution of treprostinil in water, followed by neutralization with appropriate amounts of corresponding inorganic base. However, a commercially viable synthetic route for preparation of the sodium salt of treprostinil is desired.
Preparation of treprostinil sodium can be difficult, as the salt is soluble in water and difficult to precipitate, while the treprostinil acid is only sparingly soluble in water. Salts of a compound can be useful due in part to their increased stability, bioavailability and solubility in water. Availability of treprostinil salt can also help in preparation of a formulation, including a pharmaceutical formulation.
Therefore, there is a need in the art for a process for the preparation of a salt of treprostinil. Moreover, there is a need the art for a process for the synthesis of treprostinil sodium, including a commercially viable process.